It is well known to use thermoplastic molding technology to form plastic parts within a mold or die. One such process is called plastic injection molding (PIM). In this process, polymer material is melted and subsequently injected under pressure into a mold cavity through a runner system. Some materials require a heated runner system to prevent premature freezing of the material. Once injection into the mold, the plastic is allowed to cool and solidify thereby forming the article. The molded part is then ejected and inspected for ascetics and/or structural integrity.
In some molds, a core may be inserted into the mold cavity when forming the product. The plastic material packs into the mold cavity around the core. Accordingly, some cores are set prior to injecting the molten material and must be retracted before ejecting the solidified part. Other cores remain in the mold cavity but rotate to eject the product once the mold halves have been opened. One example may include an internally threaded closure cap. In this type of product, the core unscrews from the threads to eject the part from the mold.
Historically, actuation of injecting molding machines has been characterized by the use of mechanical devices, like spindles and fluid power utilizing devices like hydraulic cylinders and hydraulic motors. While hydraulic actuators are capable of transmitting sizeable forces effectively, most hydraulic fluid is considered unsanitary when used to mold certain types of products like those produced for the medical industry.
Some injection molding machines use electrically driven devices, for example electric motors, to actuate the clamping and injection units. While somewhat restricted to lower tonnage ranges, all-electric injection molding machines have been proven effective for their intended purpose. Electric motors, interconnected to the molds, are also used to actuate moveable cores. Linearly moveable cores are usually set and pulled by a combination of components including an electric motor and a ballscrew, for example, which translates rotary motion into linear motion. However, molding machines that utilize electric motors typically drive all of the cores simultaneously and are not directly integrated with the molds. One electromotive device is interconnected to actuate all of the cores.
State of the art technology does not provide for individual control of the various cores. Furthermore, adjusting mold cores due to wear can be cumbersome and require valuable machine downtime and labor. What is needed is a system for individually actuating mold cores for independent movement during the molding cycle and for quickly and automatically adjusting mold core movement without costly down time. The embodiments of the present invention obviate the aforementioned problems.